1. Field of the Invention
The present invention relates to a metering device and a metering method, and more particularly, to a metering device and a metering method, to which a Hall sensor is applied.
2. Description of the Related Art
A conventional watt-hour meter converts current flowing through a power supply line into an appropriate scale using a current transformer (CT) and a shunt resistor and provides it to an analog-digital converter (ADC). The ADC converts an analog signal into a digital signal to provide it to a control unit such as a main control unit (MCU), and the control unit such as the MCU calculates wattage.
However, miniaturization of the CT or the shunt resistor is limited and takes high costs, and thus, miniaturization and reduction in manufacturing costs of a watt-hour meter are limited.
In addition, since the CT cannot be easily implemented as a single chip together with the ACD, the MCU, and so on, it is impossible to manufacture the CT through a system on chip (SOC) method.
In order to overcome the limitation of the conventional watt-hour meter, techniques related to the watt-hour meter to which a Hall sensor is applied have been developed.
Here, the Hall sensor, which is a sensor configured to generate a voltage according to a magnetic field using Hall Effect, is widely used to detect a magnetic field in various fields.
A magnetic field is generated around a conductive wire through which current flows in a direction perpendicular to an electric field direction, and a magnitude of the magnetic field is varied in proportion to an intensity of the current. Applying this principle, variation in the magnetic field generated due to variation in current flowing through a power supply line is output as a voltage using the Hall sensor, and an amount of current flowing through the power supply line can be calculated using a voltage signal output from the Hall sensor.
As an example of the watt-hour meter to which the Hall sensor is applied, Patent Document 1 discloses an electronic watt-hour meter including a Hall sensor, a voltage/frequency conversion unit, a multiplication/integration unit, a calculation control unit, and a display unit.
In addition, Patent Document 2 discloses a digital relay including a constant current unit configured to uniformly maintain current flowing through a Hall magnetic sensor.
Meanwhile, a conventional analog-digital converter can convert an analog signal input within a certain range into a digital signal.
That is, a signal that can be processed by the analog-digital converter is limited.
However, since the Hall sensor outputs a voltage signal in proportion to a magnetic field, when the output voltage signal departs from a process range of the analog-digital converter, the wattage cannot be obtained. Patent Documents 1 and 2 also did not point out these problems and disclose means for solving these problems.